If you have looked into medical weight loss at all, you have seen these two names over and over. They are often talked about as if they are the same thing. They are not, and the difference matters when you and a provider decide which one fits.
Semaglutide copies GLP-1, a hormone your gut releases after you eat. It slows how fast your stomach empties and turns down appetite signals in the brain. Tirzepatide acts on GLP-1 too, but it also acts on a second hormone, GIP. That dual action is the main thing that sets it apart.
The two were compared directly in SURMOUNT-5, a 72-week trial in adults with obesity and no diabetes, published in the New England Journal of Medicine in 2025. People on tirzepatide lost about 20% of their body weight on average, compared with about 14% on semaglutide. Averages hide a wide range, and your own result depends on your dose, your history, and what else you change.
Nausea, diarrhea, constipation, and vomiting are the most common with both, usually worst while the dose is being raised. Both carry an FDA boxed warning about thyroid C-cell tumors seen in animal studies, and neither is prescribed if you or a close relative has had medullary thyroid cancer or MEN2. Pancreatitis and gallbladder problems are rarer risks worth knowing about.
Brand-name versions (Ozempic and Wegovy for semaglutide, Mounjaro and Zepbound for tirzepatide) are FDA-approved. The compounded versions in Urania's catalog are prepared by licensed compounding pharmacies and are not FDA-approved or reviewed by the FDA for safety or effectiveness. Our guide on compounded vs. brand-name GLP-1s explains that difference in more detail.
Which one makes sense depends on your health history, how you tolerate side effects, and budget. A licensed provider reviews all of that before anything is prescribed.
This guide explains general information and is not medical advice. It doesn't replace a licensed provider reviewing your own history.
